In recent builds of Dolphin, there's been this new slider in the settings for adjusting the emulated CPU speed. I also saw in the android section of the forums, that on their playable games list, it shows that you can underclock the speed to make games run faster. I tried this out on Smash Bros. Brawl, and found that it ran faster on my laptop. How does this feature work? Are there any drawbacks? How can I find optimal settings to use on my laptop, if I should use this?
Thanks.

there is a problem,reduce the clockspeed make games that demand the maximum of the cpu
slowdown or lag but your emulator show then at 100vps but some games need more cpu, i tried this reduce the clock make demanding games dont able to run at full speed they make some kind of frameskip but they show 60fps but they are frame skipping
if you reduce the clock at a level that dont affect the game speed is ok
try reduce the clockspeed to 95% or 90%
in this config dont affect a bunch of games
except for the extreme demanding ones like last story and a bunch of others
REDUCE THE CLOCK MAKE GAMES RUN AT FULL SPEED BUT THEY SKIP FRAMES
BECAUSE THE GAMES NEED MORE CPU CLOCK

I'll try to give an explanation of this feature, and if I'm wrong, I'm sure one of the developers will correct me.

There are two reasons for a GC/Wii game to run slowly in Dolphin -- either the game pushes the GC/Wii hardware to the limits (in which case it might run slowly on a real GC/Wii), or Dolphin is pushing your PC to its limits (in which case the game would be running just fine on real hardware). The emulated CPU clock allows you to compensate for both problems in different ways.

Firstly, let's assume that the game pushes the GC/Wii to the limits of what the real hardware can accomplish. In this case, the game might run in slow motion, because the GC/Wii hardware can't keep up with all the things the game is trying to do. Dolphin essentially creates a virtual GC/Wii on your PC and allows the game to execute within this virtual environment. A real GC runs at 485 MHz, and as with PC hardware, overclocking the GC's CPU would let you increase the console's performance and avoid slowdown in demanding games. The problem is that since real GC hardware isn't designed to handle the extra heat and stress associated with overclocking, you'd risk damaging your GC by doing this.

Dolphin, however, doesn't have a real GC CPU -- the "CPU" is part of the emulated environment. As such, Dolphin can now let you overclock the virtual CPU, which lets games that would normally slow down on a real GC/Wii perform even better than they would on the real hardware without the potential for causing any hardware damage. If you overclocked your GC to 800 MHz, you'd probably melt down your console, but Dolphin can emulate how a GC would behave if it were overclocked to 800 MHz theoretically without side effects. There are two caveats to doing this, though.

The first is that if you overclock the virtual hardware, emulating the GC/Wii will become even more demanding. As such, you can't emulate an overclocked GC/Wii unless you were already running Dolphin flawlessly at the default clock rate. The second is that not all games will necessarily behave correctly if you do this. Remember that GC/Wii games are designed to run on stock GC/Wii hardware, so they may have certain functions which rely on the CPU being clocked at the default speed. If you change the clock rate, some games may exhibit strange problems which would not occur at the default clock rate. This is why the option warns you not to report bugs that only occur when you alter the clock rate. This is an experimental feature that may have beneficial effects but is not guaranteed to be beneficial or even work at all in every game.

Secondly, let's assume that the game would run perfectly on a real GC/Wii, but because your PC is old and slow (or because Dolphin doesn't emulate the game efficiently yet), you get poor performance. This is where underclocking the virtual CPU can come in handy. If the game doesn't push the real GC/Wii hardware to its limits, the game may not need the full 485 MHz that a real GC CPU offers, even though emulating the GC at this speed may be more than your PC can handle. To compensate for this, you can underclock the the virtual GC CPU. Doing this will reduce the system requirements for emulating the game, because you're emulating a slower CPU. If the game doesn't push the GC/Wii hardware very hard, the game may even run smoothly if you perform a small underclock. On the other hand, if the game does require the full processing power of the GC/Wii hardware, then underclocking the virtual CPU may cause poor performance. The difference is that the poor performance may manifest differently when the virtual CPU is underclocked than when it's running at the normal rate.

When the virtual CPU is running at normal speed, audio may become choppy as Dolphin struggles to play the game, and many people find the choppy audio to be annoying. If you underclock the virtual CPU, the game may stutter or run in slow motion, but the audio may be less choppy, which some people consider to be the lesser of two evils.

With this in mind, whether you overclock or underclock the virtual CPU depends upon the game you're playing, whether it is performing poorly, and why it is performing poorly. This leaves us with the following possible scenarios:

If the game is performing well, then don't change the virtual CPU's clock rate at all.

If the game is performing poorly because it's known to perform poorly on a real GC/Wii, then overclocking the virtual CPU may improve performance beyond what a real console could achieve, although doing so may also cause strange glitches, depending upon the game.

If the game is performing poorly because your PC is too slow to run Dolphin at full speed, then underclocking the virtual CPU may improve performance and reduce audio stuttering, although doing so may also cause the game to have choppy animation or have slowdown. It's up to you to decide which type of poor performance you find less annoying.

Short-ish version:
1) If a game doesn't run at 100% on your computer, and you've exhausted other options for speeding it up, underclocking may lower the in-game FPS, letting you achieve a higher % emulation speed.
2) If a game runs at 100% on your computer but the FPS itself still lags, likely because the game ran slow on the Wii itself, overclocking may increase the in-game FPS, at the cost of a lower % emulation speed.
3) Neither of this is guaranteed to work; some games will like it, others won't. At your own risk, etc.

You know, usually I try different things with an option until I find the "sweet" spot. But from not so recently Dolphin has this nice feature which displays info about each option when you hover the mouse over it. Not only that, but it also says in a nutshell if it could eventually lead to a speed up or a slow down. Pretty nice! Either way the best thing is to actually read about it and familiarize yourself with it.